RFR: JDK-8075725: Remove /jre subdir in hotspot dist dir

[Erik Joelsson]

Hello,

In JDK 9, the /jre sub directory in the jdk image has been removed. We 
should also remove this in the hotspot dist output directory and the 
corresponding import logic in the jdk build.

There are still references to /jre in hotspot.script and build.sh, but 
since I don't know how or if these files are used, I don't dare changing 
them.

Bug: https://bugs.openjdk.java.net/browse/JDK-8075725
Webrev: http://cr.openjdk.java.net/~erikj/8075725/webrev.01/

/Erik